man with a *beep* of money and knowledge building his own spacecraft and actually launching it?
You mean like Elon Musk? (google him)
The difference, of course, is that Musk doesn't build his rockets in his backyard barn with only one person to help him, and he plays ball with the government regarding permits and so forth. He is also rich and has lots of rich venture capitalists to get him going. He also has customers lined up to use his rocket for their payloads. Also, the government actually wants him to succeed, instead of blocking him like in this movie. Probably has something to do with the fact that he doesn't endanger his family and local community by handling dangerous propellants like you would handle cow manure, nor does he launch his rocket over populated land, dropping spent rocket stages into towns along the way, like Billy Bob does in the movie.
These are some of the reasons why the movie doesn't feel believable. Other than that, sure, someday some private entity WILL launch his own rockets; Musk has already tried 3 times and failed, and will try again sometime in the next few months.